146 HAEMORRHAGIC DISEASES [VOL. vi Dijje\enti(.d diagnosis fiom haemophilia Resemblance to ana- phylactoid purpuia Recognition of predisposing facto is (?) Diagnosis ami Differential Diagnosis The diagnosis is rarely difficult. Examination of the blood-cells will usually rapidly differentiate the blood diseases, such as leukaemia, but very rarely there is a close resemblance to aplastic anaemia and lymph- oid leukaemia with leucopenia. Haemophilia is distinguished by the previous history, the coagulation time, the absence of purpura, and the fact that the bleeding, when the site is visible, consists of a steady ooze at a site of trauma. There is no object in attempting to differentiate purpura haemo- rrhagica from anaphylactoid purpura in doubtful cases. The similarity of the pathogcnesis has already been referred to, and all intermediate grades are met \vith. It is important to ascertain if there are any predisposing factors such as are associated with secondary or symptomatic purpura, as this may affect decisions as to treatment, but the clinical manifestations of the primary and secondary groups are not distinguishable. Local treatment (/) Treatment Local treatment is only of use for checking gross haemorrhage from a mucous membrane. Reasonable pressure may be applied, but if this is too severe and too prolonged it may produce necrosis of the tissues. Coagulant snake venom is under trial, and the results so far have been Snake venom very promising, the most potent being the venom of Russell's viper. This is used in a dilution of 1 in 10,000 and is applied with a gauze dressing. The bleeding site must be carefully cleansed first and clots gently removed. General treatment aims at aborting the haeinorrhagic tendency temporarily or permanently. The specific measures which need careful consideration are blood transfusion and splenectomy. Blood transfusion may end the haemorrhagic tendency, apart from its direct value to an anaemic subject. It should always be performed in all cases of acute purpura haemorrhagica immediately the diagnosis has been made. The blood must be carefully grouped, and cross grouping with the prospective donor should be performed (sec Vol. IJ, p. 535), but the presence of auto-agglutinins in the patient's blood at room temperature is not a contra-indication to transfusion. The amount injected should be about 300 c.c. for an adult. (For technique see Vol. II, p. 536.) The bleeding time must be watched subsequently, and if a definite reduction does not occur in twelve hours blood transfusion should be repeated. Splenectomy Splenectorny brings to an end the haemorrhagic tendency in a high proportion of cases, but the decision to operate must not be made lightly, owing to the serious operative mortality in acute forms. It must be borne in mind that many cases recover spontaneously, and in all circumstances blood transfusion must be tried first. Splenectomy may be considered if at the end of twenty-four hours and after two blood transfusions the haemorrhages continue, the bleeding time is still General treatment Blood transfusion Grouping Technique